scholarly journals The root meristem is shaped by brassinosteroid control of cell geometry

Nature Plants ◽  
2021 ◽  
Vol 7 (11) ◽  
pp. 1475-1484
Author(s):  
Y. Fridman ◽  
S. Strauss ◽  
G. Horev ◽  
M. Ackerman-Lavert ◽  
A. Reiner-Benaim ◽  
...  
Keyword(s):  
Cell Volume ◽  
Radial Growth ◽  
Growth Regulation ◽  
Root Meristem ◽  
Three Dimensional ◽  
Strong Impact ◽  
Cell Geometry ◽  
Cell Quantification ◽  
Growth Anisotropy ◽  
Hormone Effect

AbstractGrowth extent and direction determine cell and whole-organ architecture. How they are spatio-temporally modulated to control size and shape is not well known. Here we tackled this question by studying the effect of brassinosteroid (BR) signalling on the structure of the root meristem. Quantification of the three-dimensional geometry of thousands of individual meristematic cells across different tissue types showed that the modulation of BR signalling yields distinct changes in growth rate and anisotropy, which affects the time that cells spend in the meristem and has a strong impact on the final root form. By contrast, the hormone effect on cell volume was minor, establishing cell volume as invariant to the effect of BR. Thus, BR has the highest effect on cell shape and growth anisotropy, regulating the overall longitudinal and radial growth of the meristem, while maintaining a coherent distribution of cell sizes. Moving from single-cell quantification to the whole organ, we developed a computational model of radial growth. The simulation demonstrates how differential BR-regulated growth between the inner and outer tissues shapes the meristem and thus explains the non-intuitive outcomes of tissue-specific perturbation of BR signalling. The combined experimental data and simulation suggest that the inner and outer tissues have distinct but coordinated roles in growth regulation.

scholarly journals Root meristem shaping via brassinosteroid-controlled cell geometry

2021 ◽  
Author(s):  
Yulia Fridman ◽  
Soeren Strauss ◽  
Guy Horev ◽  
Michal Ackerman-Lavert ◽  
Anat Reiner Benaim ◽  
...  
Keyword(s):  
Cell Volume ◽  
Radial Growth ◽  
Growth Regulation ◽  
Root Meristem ◽  
Strong Impact ◽  
Cell Geometry ◽  
Differential Growth ◽  
Growth Anisotropy ◽  
Hormone Effect ◽  
3D Geometry

Growth extent and direction determine cell and whole-organ architecture. How they are spatiotemporally modulated to control size and shape? Here we tackled this question by studying the effect of brassinosteroid (BR) signaling on the structure of the root meristem. Quantification of the 3D geometry of thousands of individual meristematic cells across different tissue types showed that modulation of BR signaling yields distinct changes in growth rate and anisotropy, which affects the time cells spend in the meristem and has a strong impact on final root form. By contrast, the hormone effect on cell volume was minor, establishing cell volume as invariant to the effect of BR. Thus, BR has highest effect on cell shape and growth anisotropy, regulating overall radial growth of the meristem, while maintaining a coherent distribution of cell sizes. Moving from single-cell quantification to the whole organ, we developed a computational model of radial growth that demonstrates how differential growth regulation by BR between the inner and outer tissues shapes the meristem. The model explains the unintuitive outcomes of tissue-specific perturbation of BR signaling and suggests that the inner and outer tissues have independent but coordinated roles in growth regulation.

Correlation between tympanometry volume and three-dimensional computed tomography mastoid volumetry in tympanoplasty candidates

2021 ◽  
pp. 1-5
Author(s):  
L Epprecht ◽  
L Qingsong ◽  
N Stenz ◽  
S Hashimi ◽  
T Linder
Keyword(s):  
Computed Tomography ◽  
Tympanic Membrane ◽  
Cell Volume ◽  
Radiation Injury ◽  
Three Dimensional ◽  
Non Invasive ◽  
Tympanic Membrane Perforations ◽  
Computed Tomography Scans ◽  
Air Cells ◽  
Mastoid Air Cells

Abstract Objective Ventilation of the middle ear and mastoid air cells is believed to play an important role in the pathogenesis of chronic ear disease. Traditionally, ventilation is assessed by computed tomography. However, this exposes patients to cumulative radiation injury. In cases with a perforation in the tympanic membrane, tympanometry potentially presents a non-invasive alternative to measure the ventilated middle-ear and mastoid air cell volume. This study hypothesised that total tympanometry volume correlates with ventilated middle-ear and mastoid air cell volume. Method Total tympanometry volume was compared with ventilated middle-ear and mastoid air cell volume on computed tomography scans in 20 tympanic membrane perforations. Results There was a high correlation between tympanometry and computed tomography volumes (r = 0.78; p < 0.001). A tympanometry volume more than 2 ml predicted good ventilation on computed tomography. Conclusion These results may help reduce the need for pre-operative computed tomography in uncomplicated cases with tympanic membrane perforations.

Alteration of the erythrocyte ultrastructure and blood viscosity by morphine

1978 ◽  
Vol 56 (2) ◽  
pp. 245-251 ◽  
Author(s):  
E. B. Vadas ◽  
E. A. Hosein
Keyword(s):  
Cell Volume ◽  
Blood Viscosity ◽  
Whole Blood ◽  
Plasma Viscosity ◽  
Cell Geometry ◽  
Flow Properties ◽  
Mean Cell Volume ◽  
Morphine Administration ◽  
The Mean ◽  
Volume Cell

The effects of acute morphine administration on intact erythrocytes and on their flow properties were studied by measuring the mean cell volume, cell geometry, and whole blood and plasma viscosities. Morphine caused a small (2–7%) increase in mean cell volume. Changes in cell geometry were found to be time dependent and most pronounced in concave portions of the red cells. Whole blood viscosity was found to decrease upon morphine treatment; this may be due in part to a concurrent decrease in plasma viscosity.

scholarly journals Cow Milk Lactoferrin Possesses Several Catalytic Activities

Biomolecules ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 208 ◽  
Author(s):  
Svetlana E. Soboleva ◽  
Sergey E. Sedykh ◽  
Ludmila I. Alinovskaya ◽  
Valentina N. Buneva ◽  
Georgy A. Nevinsky
Keyword(s):  
Transcriptional Activation ◽  
Growth Regulation ◽  
Rna Binding ◽  
Viral Infections ◽  
3D Structure ◽  
Three Dimensional ◽  
Physiological Role ◽  
Protective Role ◽  
Cow Milk ◽  
Dna And Rna

Lactoferrin (LF) is a Fe3+-binding glycoprotein, that was first recognized in milk and then in other epithelial secretions and barrier body fluids to which many different functions have been attributed to LF including protection from iron-induced lipid peroxidation, immunomodulation, cell growth regulation, DNA and RNA binding, as well as transcriptional activation, etc. The polyfunctional physiological role of LF is still unclear, but it has been suggested to be responsible for primary defense against microbial and viral infections. It was shown previously that human milk LF possesses several enzymatic activities: DNase, RNase, ATPase, phosphatase, and amylase. Analysis of human, cow, horse, buffalo and camel LF showed a highly conserved three-dimensional (3D) structure including only detail differences in the species. Recently, it was shown that similar to human cow LF possesses DNase and RNase activities. Using different methods here we have shown for the first time that LFs from the milk of seven cows of different breeds possess high peroxidase, protease, amylase, protease, and phosphatase activities. Protease activity of cow LFs was activated by Mg2+ and Ca2+ ions. In contrast to human LFs, ATPase activity was revealed only in three of seven cow LF preparations. The discovery that LF possesses these activities may contribute to understanding the multiple physiological functions of this extremely polyfunctional protein including its protective role against microbial and viral infections.

A novel multiaxial three-dimensional woven preform: Process and structure

2017 ◽  
Vol 37 (4) ◽  
pp. 247-266 ◽  
Author(s):  
Xinmiao Wang ◽  
Li Chen ◽  
Junshan Wang ◽  
Xintao Li ◽  
Zhongwei Zhang
Keyword(s):  
Cross Sections ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Woven Composite ◽  
Cell Geometry ◽  
Geometry Model ◽  
End Use ◽  
Experimental Values ◽  
Composite Samples ◽  
Good Agreement

A novel multiaxial three-dimensional woven preform and the weaving technique have been developed in this study. The preform exhibits remarkable designs, which is formed by multiple layers of different yarn sets, including bias (+bias/−bias), warp, and filling, and all layers are locked by Z-yarns These layers are arranged in a rectangular fashion and the layer number and the position of bias layer can be determined by the end-use requirements. A weaving process and machine are proposed to produce the preform. The weaving technique enables the insertion of many warp layers between two opposite bias layers. The microstructure of the preform was also studied. Microscopic evidence of the microstructure reveals that the cross-sections of Z-yarn are variable along its central axis due to the lateral compression forces of adjacent yarns from different directions. On the basis of microscopic observation, a unit cell geometry model of multiaxial three-dimensional woven preform is established, and a good agreement has been obtained between the theoretical and experimental values of the structural parameters of woven composite samples.

scholarly journals ON THE PLASTIDS, MITOCHONDRIA, AND OTHER CELL CONSTITUENTS DURING OÖGENESIS OF A PLANT

1966 ◽  
Vol 28 (3) ◽  
pp. 527-543 ◽  
Author(s):  
Lothar Diers
Keyword(s):  
Electron Microscopy ◽  
Cell Volume ◽  
Mother Cell ◽  
Developmental Stages ◽  
Three Dimensional ◽  
Egg Cell ◽  
Lipid Bodies ◽  
Growth Phases ◽  
Quantitative Investigation ◽  
Nucleus Volume

In the liverwort Sphaerocarpus donnellii Aust., the behavior of the cell constituents, especially of mitochondria and plastids, was studied by electron microscopy during the development of the egg and its preceding cells. A degeneration and elimination of mitochondria and plastids was not found in any of the developmental stages. In all growth phases of the archegonium, the plastids may deposit starch which becomes especially frequent in the maturing egg cell. No indications have been observed that new mitochondria or plastids generate from the nuclear evaginations, which often penetrate deeply into the cytoplasm of the maturing and fully developed eggs. A quantitative investigation based on general micrographs elucidates the numerical aspects of the cell constituents during oögenesis. With the increase of cell volume, the numbers of dictyosomes, mitochondria, plastids, and lipid bodies increase. From the stages of the mother cell of the axial row up to that of the mature egg, the cell volume enlarges about 8 times and the nucleus volume about 15 times. Simultaneously, the numbers of mitochondria and plastids increase up to 8 to 15 times. On the basis of these findings, mitochondria and plastids with three-dimensional narrow constrictions are interpreted as divisional stages.

Three dimensional structure of the leishmania amastigote as revealed by computer-aided reconstruction from serial sections

Parasitology ◽  
1986 ◽  
Vol 92 (1) ◽  
pp. 13-23 ◽  
Author(s):  
G. H. Coombs ◽  
L. Tetley ◽  
V. A. Moss ◽  
K. Vickerman
Keyword(s):  
Cell Volume ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Serial Sections ◽  
Leishmania Mexicana ◽  
Cell Organelles ◽  
3 Dimensional ◽  
Computer Aided ◽  
Total Cell Volume

SUMMARYComputer-aided reconstruction from serial sections has been used to analyse the 3-dimensional structure of entire amastigotes of Leishmania mexicana mexicana and to determine the number, arrangement and volume of each organelle. In two reconstructions, the lysosome-like ‘megasomes’ were the most numerous organelle, there being 34 in one amastigote, and they comprised as much as 15% of the total cell volume. In contrast, as few as 9 glycosomes were present, accounting for less than 1% of the cell volume. The unitary nature of the mitochondrion was confirmed and its complex basket-like structure was revealed. The spatial arrangement of the cell organelles is here displayed in stereo-pairs.

Electron–phonon interaction in three-, two- and one-dimensional ternary mixed crystals

2016 ◽  
Vol 30 (15) ◽  
pp. 1650182
Author(s):  
Junhua Hou ◽  
Yunpeng Fan
Keyword(s):  
Cell Volume ◽  
Effective Mass ◽  
Unit Cell Volume ◽  
Three Dimensional ◽  
Unit Cell ◽  
Mixed Crystals ◽  
Phonon Interaction ◽  
One Dimensional ◽  
Electron Phonon Interaction ◽  
Self Trapping

The electron–phonon (e–p) interaction in three-dimensional (3D), two-dimensional (2D) and one-dimensional (1D) ternary mixed crystals is studied. The e–p interaction Hamiltonians including the unit cell volume variation in ternary mixed crystals are obtained by using the modified random-element-isodisplacement model and Born–Huang method. The polaronic self-trapping energy and renormalized effective mass of GaAs[Formula: see text]Sb[Formula: see text], GaP[Formula: see text]As[Formula: see text] and GaP[Formula: see text]Sb[Formula: see text] compounds are numerically calculated. It is confirmed theoretically that the nonlinear variation of the self-trapping energy and effective mass with the composition is essential and the unit cell volume effects cannot be neglected except the weak e–p coupling. The dimensional effect cannot also be ignored.

scholarly journals ABA represses TOR and root meristem activity through nuclear exit of the SnRK1 kinase

2021 ◽  
Author(s):  
Borja Belda-Palazon ◽  
Monica Costa ◽  
Tom Beeckman ◽  
Filip Rolland ◽  
Elena Baena-Gonzalez
Keyword(s):  
Cell Proliferation ◽  
Nuclear Export ◽  
Growth Regulation ◽  
Root Meristem ◽  
Plant Tolerance ◽  
Proliferation Zone ◽  
Meristem Size ◽  
Main Driver ◽  
Root Meristematic Cells ◽  
Underlying Mechanisms

The phytohormone abscisic acid (ABA) promotes plant tolerance to major stresses like drought, partly by modulating plant growth and development. However, the underlying mechanisms are poorly understood. Here, we show that cell proliferation in the Arabidopsis thaliana root meristem is controlled by the interplay between three kinases, SNF1-RELATED KINASE 2 (SnRK2), the main driver of ABA signaling, the SnRK1 energy sensor, and the growth-promoting TARGET OF RAPAMYCIN (TOR) kinase. Under favorable conditions, the SnRK1α1 catalytic subunit is enriched in the nuclei of root meristematic cells and this is accompanied by normal cell proliferation and meristem size. Depletion of SnRK2s in a snrk2.2 snrk2.3 double mutant causes constitutive cytoplasmic localization of SnRK1α1 and a reduction in meristem size, suggesting that, under non-stress conditions, SnRK2s enable growth by retaining SnRK1α1 in the nucleus. In response to elevated ABA levels, SnRK1α1 translocates to the cytoplasm and this is accompanied by inhibition of TOR, decreased cell proliferation and meristem size. Blocking nuclear export with leptomycin B abrogates ABA-driven SnRK1α1 relocalization to the cytoplasm and the inhibition of TOR. Fusion of SnRK1α1 to an SV40 nuclear localization signal leads to defective TOR repression in response to ABA, demonstrating that SnRK1α1 nuclear exit is a premise for this repression. Finally, the SnRK2-dependent changes in SnRK1α1 subcellular localization are specific to the proliferation zone of the meristem, underscoring the relevance of this mechanism for growth regulation.

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